This invention concerns improvements in and relating to materials, particularly but not exclusively of the type used to space glass and other materials during handling storage and transportation, particularly those of sheet form.
Glass sheets arrive from the manufacturers in stacks of sheets of one size in a purpose built frame. However, during subsequent processing and handling spacing elements are used to keep the individual glass element apart with a view to easing handling and avoid damage due to relative movement or foreign bodies being caught between sheets.
As many sets of spacers may be required during the overall process life of the glass spacers must be cheap to produce; and not damage the glass as well as offering suitable padding levels. Above all the spacers must be easily applied and removed.
A number of different materials can and have been employed as spacers.
Amongst the earliest techniques was the introduction of a piece of paper between the sheets. However, paper offers limited crush resistance or padding and is awkward to handle.
As an alternative the provision of spacers as a series of discrete blocks which are placed at various locations on the glass has been used. A number of such spacer types exist, such as cork and PVC composites or a foam pad. When applied without an adhesive on one side to hold the pad in position the spacer frequently and inconveniently falls off. When provided with an adhesive the spacer sometimes bonds too well and is difficult to remove, decreasing productivity.
It is an aim of the present invention to meet these objectives whilst providing a spacer which can easily be introduced to and removed from its location of use.
According to a first aspect of the invention we provide a spacer adapted, in use, to space materials comprising a spacer element the spacer element having on at least one face an adhesive wherein at least a portion of the edge of said adhesive carrying face is adhesive free.
In this way a finger or other means employed to remove the spacer can easily do so as a portion of the edge is easily liftable relative to the spaced element.
The spacer is preferably sufficiently flexible that a part of it (e.g. a non-adhesive peripheral portion) can be bent out of the plane of the remaining, bonded, part of it so as to assist in gripping the spacer to remove it. Thus a xe2x80x9cfingerliftxe2x80x9d edge portion is provided.
Preferably the adhesive is provided in one or more stripes. An easy manner for introducing the adhesive is thus allowed. Most preferably the stripes are substantially perpendicular to an edge of the spacer. This gives regular positioning of the adhesive on a series of spacers.
The adhesive may be provided in a central portion of the spacer, so providing a large amount of edge free. Alternatively, or additionally, the adhesive may follow one or more edges, leaving one or more other edges or portions thereof, free.
The adhesive carrying areas themselves may consist of a continuous or discontinuous layer of adhesive. Thus the adhesive may be provided as dots, cross-hatching or the like to give the desired degree of adhesion and level of adhesive use.
According to a second aspect of the invention we provide a method of manufacturing a plurality of spacers comprising:
a) forming the spacer material
b) applying continuous discontinuous adhesive to the spacer material
c) cutting the spacer material into a plurality of spacers,
wherein one or more of the cut edges of the spacer includes a portion of spacer material which is free of adhesive.
In this way the fingerlift function is achieved as a xe2x80x9cdry edgexe2x80x9d is provided.
Steps b) and c) may be reversed whilst achieving the same result.
Preferably each spacer generated has an edge portion without adhesive but a degree of wastage is acceptable.
Preferably the adhesive is applied in stripes. Most preferably the application is parallel to the direction of advancement of the spacer material through the adhesive applying stage.
The adhesive may be applied in stripes between three quarters and a fifth of the width of the spacer to be cut although the adhesive may be wider or narrower. An equivalent or larger or smaller width may be provided between adjacent adhesive stripes or adhesive free areas. The effect may be achieved by multiple stripes or other form of discontinuous adhesive (e.g. dots)
Whilst an adhesive may be applied to the spacer as a continuous covering alternatively it may be in a discontinuous form, such as a pattern, series of dots or strips which may aid the use or manufacture as well as reducing manufacturing costs. The use of discontinuous adhesives is particularly advantageous where it is desired to apply the spacer by means of semi-automatic or automatic dispensers as are currently employed on production lines or in other continuous manufacturing environments.
Particularly preferred type of adhesives are the pressure-sensitive types which will readily hold the component in place during use but will easily and cleanly remove from the glass and/or other material when no longer required.
The spacer may have its adhesive covered by protective release paper to aid manufacture of the pads and dispensing and eventual use/application of same.
By cutting spacer material into the required size during manufacture and using external glue to join adjoining sheets a spacer material or layers of a roll of spacer material temporarily, the product can economically be provided in easily handled form.
Alternatively the externally applied adhesive may be incorporated into the manufacture of the spacer material. Such an adhesive may be applied prior to or when cutting the spacer material to make rolls or sheets of spacers.
When supplied in rolls, the product may be provided in various lengths and widths as necessary to ease its use with specialist application equipment or by hand. Where such equipment is used, the dispensers themselves may serve to cut the spacers at the required size and/or apply them to the glass and or other materials.
Where a backing is provided the die may cut through the spacer material and leave the backing intact.
Preferably the die cuts through the spacer material and partly cuts the backing material providing a construction which allows lengths of product to be removed from a roll.
The partial cutting may comprise providing a cut at either side of the backing material. Alternatively, it may comprise providing perforations or cuts across the width of the backing material.
In another embodiment of the present invention there is provided a stack of two or more sheets of glass (or other material) wherein each sheet is separated by one or more spaces according to the first aspect of the invention.
In yet another embodiment of the present invention there is provided a sheet of material having a first and second face, the sheet having on at least one of the faces a number of stripes of glue, the sheet being adapted, in use, to be cut into spacers according to the first aspect of the invention.